Method and apparatus for capturing oil leaking from an underwater well

ABSTRACT

A system for capturing oil leaking from an underground well includes an elongate hollow tube which is deployed vertically in the water with its open lower end located above the oil well. A system for securing the tube in the desired location where it captures the maximum amount of leaking oil includes an adjustment system which allows the tube to be moved transversely once it is in place. A method is provided for erecting the tube and anchoring it at the desired location above the leaking well.

BACKGROUND OF THE INVENTION

When oil wells are located under water, it can be difficult and timeconsuming to cap them if an accident occurs and there is uncontrolledleakage of oil from the well. While there are procedures for capping orotherwise plugging underwater wells, a considerable amount of oil canflow out of the well before it can be capped. This leakage can causeextensive environmental damage and there can be considerable costsinvolved in attempting to capture the oil that is discharged from thewell before the well is capped.

BRIEF SUMMARY OF THE INVENTION

A system for capturing oil leaking from an underwater well includes anelongate hollow tube which is deployed vertically in the water above thewell. An anchoring system which anchors the tube to the floor beneaththe body of water includes an adjustment system which allows moving thetube transversely to a location where it captures the maximum amount ofoil. A method is provided for constructing the tube from a plurality oftube segments, and erecting it above a leaking oil well.

The foregoing and other objectives, features, and advantages of theinvention will be more readily understood upon consideration of thefollowing detailed description of the invention, taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a side elevation view of a system for capturing oil from aleaking well embodying the subject invention.

FIG. 2 is a perspective view, looking from above, of the system of FIG.1.

FIG. 3 is a side elevation view similar to FIG. 1, showing how the tubethat is used to capture the oil can be moved transversely.

FIG. 4 is a partial perspective view showing a first embodiment of atube segment, which is an element of the subject invention.

FIG. 5 is a partial perspective view showing another embodiment of atube segment.

FIG. 6 is a perspective view of the tube segment shown in FIG. 5 in acollapsed position.

FIG. 7 is a side elevation view illustrating one method of constructingthe system.

FIGS. 8 and 9 are perspective views, similar to FIG. 2, showing methodsfor constructing the system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to FIG. 1 of the drawings, an elongate hollow tube 10 isdeployed in a vertical orientation over a leaking underwater oil well.The tube 10 has an upper end 12, FIG. 8, which is located proximate thesurface of the water, and a lower end 14, which is located substantiallybelow the surface of the water, but above the floor 16 of the body ofwater. How far the lower end is above the floor depends upon thediameter of the tube, the velocity which the leaking oil exits the floor16, and the extent of water currents between the floor and the lower end14. However, it preferably is located close enough to the floor so thata large portion of the oil 18 escaping from the well is still travelingsubstantially vertically upwardly and has not dispersed substantially towhere a significant portion of it flows into the lower end of the tube.The tube is open at both ends, but a domed shape collection chamber 20covers its upper end 12. A plurality of flotation devices 22 areattached to the tube around its outer surface to support the tubevertically at the appropriate depth. Providing this neutral buoyancycould be achieved by other means. Referring now also to FIG. 2, thecollection chamber 20 and upper end 12 of the tube project through anopening 23 in a flotation platform 24 which is shown schematically.Flotation platforms of this type are well known in the offshore oil welltechnology. Attached to the platform 24 at generally equally spacedlocations around the tube are a plurality of floats 26. In theembodiment illustrated, there are four floats, but there could be anynumber of floats. The floats 26 are attached to the platform 24 to forman integral floating unit. Each float is anchored to the floor 16 bymeans of a cable 28 which extends between the float and a platformanchor 30 located on the floor 16. The platform anchors 30 are locatedaround a circle circumscribed on the floor 16 having a diameter which ismuch larger than the diameter of the tube 10, in order to maintain thetube in generally the same location.

An anchoring system anchors the lower end of the tube 10 to the floor16. The platform 24 and the anchoring system work together to maintainthe tube 10 in its vertical orientation. The anchoring system includesan adjustment system 32 which permits the tube to be moved laterally inorder to initially locate it above the escaping oil 18 and to keep it inthe optimal location to capture the maximum amount of the oil. Locatedon each float 26 is a take-up device 34 having a cable 36 attached toit. In the embodiment shown in the drawings, the take-up device is awinch, but it could be another type of device. The cables 36 aredirected downwardly along the length of the tube by passing them throughguides 38 located on the outer surface of the tube. The guides could berollers such as shown, or any other device which will allow a cable tomovably extend along the longitudinal length of the tube. The bottoms ofthe cables 36 are attached to tube anchors 40 located on the floor 16.In the embodiment, the tube anchors 40 are located on a circlecircumscribed on the floor 16 having a diameter which is greater thanthe diameter of the tube 16 and less than the diameter of the circle thefloat anchors are located around. Referring now also to FIG. 4, by usingthe take-up devices 34 to shorten a cable 38 a onto its associatedtake-up device 34 and lengthening the cable 28 b on the opposite take-updevice 34. The tube 10, platform 24, and floats 26 will be movedlaterally.

In order to facilitate erection of the tube 10, it is constructed from aplurality of tube segments 42 which are joined end-to-end, FIGS. 4 and5. In the embodiment shown in FIG. 4, the tube segments 42 a have asolid wall 44 with flanges 46 at each end. The wall 44 could beconstructed from metal or another rigid material.

The tube segments 42 b, shown in FIGS. 5 and 6, are collapsible. Thecollapsible tube segments 42 b have a plurality of annular rings 48which support a flexible wall 50. The wall 50 could be a fabricmaterial, such as rubberized canvas, or any other flexible materialwhich can function in this environment. The rings 48 are made from metalor other suitable rigid material. The rings at each end of each tubesegment 42 b serve as the flanges which are used to attach adjacent tubesegments to one another. The flexible tube segments 42 b collapse bytheir own weight when placed on a solid surface, FIG. 6, but by coveringthe ends of the tube segment and drawing a vacuum through a line 52, thewall 50 will be pulled inwardly when the tube segment is collapsed sothat it is out of the way. In order to strengthen the collapsible tubesegments and facilitate hanging them vertically, longitudinal straps 54may be attached to the rings 48 at selected intervals around theperiphery of the tube segment. The tube segments 42 can be attached toone another by bolting, riveting, installing collars, or by other knownmeans. Holes 56 are shown in the flanges to facilitate this. The tube 10can either be assembled remote from the leaking well and towed to thesite of the well, FIG. 7, or erected at the site of the well, FIGS. 8and 9. One way of accomplishing the former is to assemble the tubesegments 42 onshore and pull them into the water as additional tubesegments are attached, FIG. 7. Covers 58 cover both ends of the tube sothat air trapped in the tube causes it to float. When the tube has beentowed to the site, the cables 36 from the take-up devices 34 are fedthrough the guides 38 and attached to the tube anchors 40. Appropriateflotation devices 22 are attached to the tube to provide neutralbuoyancy and the cover 58 is removed from what will be the lower end ofthe tube. This will allow water to flow into the tube and the tube willsink lower end first. The filling of the tube with water and theflotation devices cause the tube to become vertical with its upper endadjacent to the surface of the water. The cover 58 at the upper end ofthe tube is removed and a crane 16 located on one of the floats 26 thenplaces the collection chamber 20 on top of the tube and the collectionchamber and tube are joined, FIG. 2. While this erection method could beused with either solid tube segments 42 a or collapsible tube segments42 b, it is shown in the drawings with solid tube segments 42 a becausethis method would more commonly be used for erecting the tube 10 fromsolid tube segments 42 a.

Erecting the tube 10 on the site would most commonly be used forerecting the tube from collapsible tube segments 42 b. Referring now toFIG. 9, the crane 62 is used to lift collapsible tube segments off of abarge or similar floating storage structure (not shown). The crane thenlowers the tube segment through the opening 23 in the platform 24 intothe water, and the tube segment is allowed to expand. Flotation devices22 are attached to this tube segment so that it floats with its upperend 12 near the surface of the water. The crane 62 is then disconnectedfrom this tube segment and is attached to another collapsed tube segment42 b. The new tube segment is then placed over and lowered against theprevious tube segment. The two tube segments are then attached andadditional flotation devices are attached so that the combined tubesegments have neutral buoyancy. The process is then repeated until thetube has reached the desired length. Cables 36 are then fed throughguides 38 and attached to the tube anchors 40. Finally, the crane isused to place the collection chamber 20 on top of the tube. Regardlessof which erection method is used, after the tube is erected, oil 18 fromthe leaking well rises through the water in the tube, due to its lowerdensity, until it reaches the collection chamber 20. Any natural gascontained in the oil raises to the top of the collection chamber whereit is removed through a natural gas line 64. The natural gas iscollected for use or is burned. Oil is removed from the collectionchamber 20 by means of oil lines 64 and its pumped to a tanker or bargefor transportation.

The tube 10 can be erected either before the well is drilled or after itis drilled, including after a leak has occurred.

The terms and expressions which have been employed in the foregoingspecification are used therein as terms of description and not oflimitation, and there is no intention, in the use of such terms andexpressions, of excluding equivalents of the features shown anddescribed or portions thereof, it being recognized that the scope of theinvention is defined and limited only by the claims which follow.

1. A system for capturing oil leaking from an underwater wellcomprising: (a) an elongate hollow tube deployed in a verticalorientation above a leaking well, said tube having an upper end which isproximate the surface of the water and a lower end which issubstantially below the surface of the water; and (b) an anchoringsystem for anchoring the lower end of said tube to the floor below thewater.
 2. The system of claim 1 including an adjustment systemassociated with said anchoring system which allows said tube to be movedto an optimum location where it captures the maximum amount of oilleaking from said well.
 3. The system of claim 1 including buoyancydevices attached to said tube in order to support said tube with itsupper end proximate the surface of the water.
 4. The system of claim 1wherein said tube comprises a series of tube segments joined to oneanother end-to-end.
 5. The system of claim 4 wherein said tube segmentshave a solid metal wall.
 6. The system of claim 4 wherein said tubesegments are collapsible.
 7. The system of claim 6 wherein said tubesegments comprise two or more rigid rings and a flexible wall made froma fabric material, which is supported by said rings.
 8. The system ofclaim 7 wherein said fabric material is rubberized canvas.
 9. The systemof claim 7 including straps which are attached to and extend betweenadjacent rings at spaced apart locations around the periphery of saidrings.
 10. The system of claim 4 wherein said tube segments haveoutwardly projecting flanges at each end thereof and said tube segmentsare joined to one another by attaching flanges from adjacent tubesegments to one another.
 11. The system of claim 10 wherein saidadjacent tube segments are welded to one another.
 12. The system ofclaim 10 wherein said adjacent tube segments are bolted to one another.13. The system of claim 10 including a clamp ring which clamps flangesof adjacent tube sections to one another.
 14. The system of claim 1including a collection chamber which is connected to the upper end ofsaid tube.
 15. The system of claim 14 including one or more conduits forremoving oil from said collection chamber.
 16. The system of claim 14including one or more conduits for removing natural gas from saidcollection chamber.
 17. The system of claim 1 wherein the lower end ofsaid tube has a sufficiently large diameter and is located sufficientlyclose to the floor of the body of water that a large portion of the oilleaking from the well flows into said tube as it rises to the surface.18. The system of claim 2 wherein said anchoring system includes atleast three cables having lower ends which are attached to the floorbelow the water at generally evenly spaced intervals around a circlecircumcised on said floor, said circle having a diameter which isgreater than the diameter of said tube.
 19. The system of claim 17wherein said adjustment system comprises: (a) guides located on saidtube which allow said cables to extend moveably along the linear extentof said tube; (b) a take-up device associated with each of said cableslocated at the surface of said body of water; and (c) said take-updevices being capable of lengthening or shortening the amount of theassociated cable which is located in the water.
 20. The system of claim19 where said take-up devices are winches.
 21. The system of claim 18wherein said cables are located in pairs which are diametrically opposedfrom one another around the periphery of said tube.
 22. The system ofclaim 21 wherein said take-up devices are synchronized so that when oneof said cables is shortened, the opposed cable is lengthened like amount.
 23. A method of constructing the system of claim 4 comprising:(a) placing a first one of said tube segments on its side adjacent tothe water with the end facing the water covered with a first removablecap; (b) attaching the end of said first tube segment to a towing vessellocated in the water; (c) attaching another tube segment to the existingtube segment; (d) using said vessel to pull said first tube segment intothe water; (e) repeating steps (c) and (d) until the resulting tube hasthe desired length; (f) covering the unattached end of the resultingtube with a second removable cap; and (g) using said vessel to tow saidtube to an underwater well.
 24. The method of claim 23 including thefollowing additional steps: (a) attaching an anchoring system to saidtube to anchor said tube to the floor below the water; and (b) removingthe second removable cap from said tube allowing said tube to submerge.25. The method of claim 24 including attaching buoyancy devices to saidtube such that when submerged it is oriented vertically with an upperend located proximate the surface of the water and a lower end which issubstantially below the surface of the water.
 26. The method of claim 25including providing an adjustment system to said tube which allows saidtube to be moved transversely in the water.
 27. A method of constructingthe system of claim 6, comprising: (a) providing a plurality ofcollapsed tube segments at a location above said oil well; (b) expandingone of said collapsed tube segments and suspending it above the water;(c) expanding another collapsed tube segment and attaching it to the topof said one of said tube segments; and (d) repeating steps (b) and (c)until the resulting tube has the desired length.
 28. The method of claim27 including attaching buoyancy devices to said tube such that whensubmerged said tube is oriented substantially vertically with an upperend located proximate the surface of the water.
 29. The method of claim28 including attaching an anchoring system to said tube to anchor saidtube to the floor below the water.
 30. The method of claim 29 includingproviding an adjustment system which allows said tube to be movedtransversely in the water.